1. Field of the Invention
The present invention relates to a method and apparatus for estimating the dynamic state amount of a tire when a load or lateral force is applied to the tire and a tire with sensors at the inner liner portion of a tire tread for measuring the amount of deformation of the tire while running.
2. Description of the Prior Art
To enhance the running stability of an automobile, it is desired that force (tire generation force) generated in the tire such as a load, lateral force or longitudinal force should be estimated accurately and fed back to the control system of the automobile. It is considered that higher level of control of an ABS brake or a body attitude controller making use of this would become possible with this information, thereby further improving safety.
As means of estimating force generated in a tire by using the tire like a sensor in the prior art, there is proposed a method in which a tire side portion is magnetized and the twisting degree of the above tire side portion is measured with magnetic sensors installed outside the tire to estimate the longitudinal force of the tire, or lateral force generated in the tire is estimated from the size of the detection output of the above magnetic sensors, making use of the fact that the whole belt ring is deformed when lateral force is applied to the tire (refer to patent document 1, for example).
Meanwhile, there is disclosed a technology for estimating the dynamic state of a tire by comparing a measurement waveform profile by installing a plurality of acceleration sensors on the inner side of a tread on the same cross-section of the tire (refer to patent documents 2 and 3, for example).    Patent document 1: WO 01/092078    Patent document 2: WO 03/082643    Patent document 3: WO 03/082644